Warren Buffett is famous for his rules of investing: When a management with a reputation for brilliance tackles a business with a reputation for bad economics, it is usually the reputation of the business that remains intact. You should invest in a business that even a fool can run, because someday a fool will. And perhaps most famously, Never invest in a business you cannot understand. So when Buffett's friend and longtime partner in Berkshire Hathaway (BRKB), Charlie Munger, suggested early last year that they invest in BYD, an obscure Chinese battery, mobile phone, and electric car company, one might have predicted Buffett would cite rule No. 3 above. He is, after all, a man who shunned the booming U.S. tech industry during the 1990s.